Mass and Charge Transfer in a Polymeric NiSalen Complex at Subzero Temperatures

Electrochemical energy storage systems have a wide range of commercial applications. They keep energy and power even at temperatures up to +60 degrees C. However, the capacity and power of such energy storage systems reduce sharply at negative temperatures due to the difficulty of counterion injection into the electrode material. The application of organic electrode materials based on salen-type polymers is a prospective approach to the development of materials for low-temperature energy sources. Poly[Ni(CH(3)Salen)]-based electrode materials synthesized from different electrolytes were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and quartz crystal microgravimetry at temperatures from -40 degrees C to 20 degrees C. By analyzing data obtained in various electrolyte solutions, it was shown that at subzero temperatures, the process of injection into the polymer film, together with slow diffusion within the film, predominantly limit the electrochemical performance of electrode materials based on poly[Ni(CH(3)Salen)]. It was shown that the deposition of the polymer from solutions with larger cations allow the enhancement of the charge transfer due to the formation of porous structures facilitating the counter-ion diffusion.

Automated summary

Electrochemical energy storage systems have widespread commercial applications and can maintain energy and power even at high temperatures. However, their capacity and power decrease significantly at negative temperatures due to difficulties in injecting counterions into the electrode material. The use of organic electrode materials based on salen-type polymers shows promise in developing low-temperature energy sources. Experimental analysis of poly[Ni(CH(3)Salen)]-based electrode materials synthesized from various electrolytes revealed that at subzero temperatures, the electrochemical performance is primarily limited by the injection process into the polymer film and slow diffusion within the film. Deposition of the polymer from solutions with larger cations improves charge transfer by facilitating counter-ion diffusion through the formation of porous structures.